That is really good news. It has long been my #1 gripe with iMac's that you had to throw out the baby with the bathwater when they "died" or needed to be euthanized for new PC tech. Horribly inefficient and bad for the environment. Plus, now that these use high-quality IPS panels like Apples standalone displays, it makes them a really good choice. I'm glad this new feature is getting some media notice.
That said, I think that a 30" Dell is a bad comparison. A 27" Dell monitor (lower res & no LED, but 110% color gamut, brighter, and HDCP support) is currently $879 (~$570 if you watch out for good deals) making the Mac "included" in the $1700 Apple monitor far from free.